What with the Mississippi “personhood” amendment up for a vote today and also the Vatican Adult Stem Cell Conference beginning tomorrow, I thought today was a good time for a post about adult versus embryonic stem cells.

Does stem cell research have to be either/or?

Adult or stem?

Can’t someone be for both adult and embryonic stem cell research?

Can a scientist study both?

In fact, most scientists are working on both adult and embryonic stem cells, which are both very cool.

So if adult and embryonic stem cells are both so amazing, what’s the difference? Why do some people extol one type at the expense of the other? What are their relative strengths and weaknesses? Why would the Vatican spend a ton of money organizing a conference (see speaker list here) just on adult stem cells and specifically exclude embryonic stem cells?

Below are listed some key points that help us think about these questions.

1) Adult stem cells, while not definitively safe, are established to have relatively lower tumorigenic potential. In a general sense, adult stem cells are safer than ES cells, but this does not mean that all adult stem cell-based therapies are inherently safe and it does not mean that ES cell-based therapies are unsafe. Safety is still critically important to prove for potential both embryonic and adult stem cell therapies. So far, Geron and ACT both seem to have very encouraging signs that ES cell-based stem cell drugs can be safe. However, if safety were your only issue, then in a black and white world, it is accurate to say that in a general sense, adult stem cells have an advantage.

2)ES cells are relatively new and less well known than adult stem cells. In the human form, ES cells were produced only about a dozen years ago, many decades after adult stem cells. What this means is that it is unreasonable to compare adult and ES cells in terms of our knowledge base or the extent of their use at this time. Some people do this kind of comparison to say that ES cells are worthless compared to adult stem cells, but that is a meaningless argument. Arguing something like that would have been like saying in the 1970s that the new Apple computers were worthless compared to IBM simply because Apples were newer…as we know, sometimes new things come on the scene and take time to evaluate and over time things can change. We cannot abandon all new technology simply because it is new. Sometimes we have to consciously avoid bias against new technology, but it is also true that in some contexts new technology can have an allure just because of its newness. However, that is not the case for ES cells in my opinion.

3) ES cells are in a general sense far more powerful than adult stem cells. ES cells happily turn into many different kinds of differentiated tissues. Adult stem cells simply cannot do that. Period. Some people may argue otherwise, but I have seen no convincing evidence of that. My friend Don C. Reed used a great analogy about the difference between ES cells and adult stem cells. If someone is going to give you a present, would you rather have cash, which you can spend on anything or even save, or a gift card for just one specific store? Of course, cash. It’s flexible. In this analogy, ES cells are cash and adult stem cells are a gift card.

4) Reality: most stem cell researchers study multiple types of stem cells. For most of us, the classification into “adult stem cell researcher” or “embryonic stem cell researcher” is artificial because we study many kinds of stem cells. Similarly, non-scientists can be for both adult and embryonic stem cell research. It is not an either or proposition. You can be a good, moral person and even one who believes in God and support all kinds of stem cell research. Don’t let opponents of ES cell research make you feel bad for your support of ES cell research.

5) Living, breathing, thinking human beings should count in the equation too. Sometimes I think opponents of ES cell research have such tunnel vision that they forget that there are billions of living, breathing human beings out there on Earth, many of whom need help for various illnesses or injures, but for whom current medicine cannot be helpful. As I said in the previous post (Horton is wrong), we cannot endow cells with so many rights that we deprive actual human beings of rights.